Large-scale study shows risk of breast and ovarian cancer differs by type of BRCA1, BRCA2 mutation.
In a study involving more than 31,000 women with cancer-causing mutations in the BRCA1 or BRCA2 genes, researchers at The Basser Center for BRCA, the Abramson Cancer Center, and the University of Pennsylvania identified mutations that are associated with significantly different risks of breast and ovarian cancers. The researchers state the results, which show that some mutations confer higher risks of breast cancer, while other mutations show higher risks of ovarian cancer, may lead to more effective cancer risk assessment, care and prevention strategies for health care providers and carriers.
The medical community have made a lot of progress toward understanding how to reduce the cancer risks associated with inherited mutations in BRCA1 or BRCA2 mutations, but until now, little has been known about how cancer risks differ by the specific mutation a woman has inherited, explain the team. The data findings are a first step in understanding how to gain a precise risk assessment around a woman’s specific mutation, which can help guide carriers and providers in the cancer prevention decision-making process.
The current study evaluated cancer diagnoses for 19,581 carriers of BRCA1 mutations and 11,900 carriers of BRCA2 mutations. The team then analyzed whether the BRCA1 and BRCA2 mutation type or location was correlated to breast and/or ovarian cancer risk. The team identified regions of both BRCA1 and BRCA2 that, when mutated, confer higher risks of ovarian cancer, and other regions that confer higher risk of breast cancer.
The researchers state that previously, a woman with a BRCA1 mutation would have been thought to have a 59 percent risk of breast cancer and a 34 percent risk for ovarian cancer, up until age 70. However, the new research suggests that women who carry a specific subset of BRCA mutations most commonly present in the Ashkenazi Jewish population have a higher risk of breast cancer (69 percent) and a lower risk of ovarian cancer (26 percent), for example. The important question that remains is whether these differences will change the decisions a woman makes about preventive surgery and other lifestyle behaviours.
With these new findings, the medical community have gained knowledge of mutation-specific risks which could provide important information for risk assessment among BRCA1/2 mutation carriers. The team surmise that additional research is needed to determine the absolute risks associated with different mutations, and how those differences might influence decision making and standards of care, such as preventive surgery, for carriers of BRCA1 and BRCA2 mutations.